System Outline

Previous automatic transmissions have selected each gear shift using mechanically controlled throttle hydraulic pressure, governor hydraulic pressure and lock-up hydraulic pressure. The electronically controlled transmission, however, controls the line pressure, throttle pressure, lock-up pressure and accumulator pressure etc. electrically via the solenoid valve. The electronically controlled transmission is a system which precisely controls gear shift timing and lock-up timing in response to the vehicle's driving conditions and the engine condition detected by various sensors. It makes smooth driving possible by selecting the gear which is the most appropriate to the driving conditions at that time, and by preventing downing, squat and gear shift shock when starting off.

1. Gear Shift Operation

   When driving, the engine warm up condition is input as a signal to TERMINAL THW of the engine control module from the engine coolant temp. sensor and the vehicle speed signal from vehicle speed sensor is input to TERMINAL SP2+ of the engine control module. At the same time, the throttle valve opening signal from the throttle position sensor is input to TERMINALS VTA1 and VTA2 of the engine control module as throttle angle signal.

   Based on these signals, the engine control module selects the best shift position for the driving conditions and sends current to the electronically controlled transmission solenoid.

2. Line Hydraulic Pressure Control

   The engine control module optimizes the line hydraulic pressure level by controlling TERMINAL SLT+ of the module according to the engine torque data. This improves the smoothness of the gear shifting.

3. High Response Gear Shifting Control

   The engine control module performs high response engine torque increases to control the ignition-timing lag as well as opening the electronic throttle when shifting down. By doing this, the gear shifting can be performed in a short period of time. Moreover, the engine control module uses the orifice switching control, which optimizes the speed of applying and reducing the hydraulic pressure. And it allows fine or smooth shifting as needed by applying and reducing hydraulic pressure slowly when the gear shifting shock is important and quickly when the high response is required.

4. Clutch Hydraulic Pressure Control

   The engine control module optimizes the clutch operation timing and hydraulic pressure according to the engine torque data and the number of clutch revolutions

5. Lock-Up and Flexible Lock-Up Control

   The engine control module carries out lockup control by adjusting TERMINAL SLU+ according to the shift position, vehicle speed, throttle opening degree and running conditions.

6. Stop Light SW Circuit

   If the brake pedal is depressed (Stop light SW on) while driving in the lock-up condition, a signal is input to TERMINAL STP of the engine control module. The engine control module activates and cuts the current to the solenoid to release the lock-up.

7. AI-Shift Control

   The engine control module judges whether the road is sloping down or up by detecting the throttle opening degree and the vehicle speed. Moreover it can predict bends in the road by detecting the turning condition of the vehicle. The engine control module can prevent unnecessary shifting above the fourth gear and, if necessary, automatically shift down to the third gear in order to improve the vehicle handling. The engine control module also reads the driver's intentions during driving from their accelerating operation and the running conditions of the vehicle. As a result, an ideal shifting pattern for each driver can be automatically selected without any manual switching operations being required.